CVE-2023-36839
Junos OS and Junos OS Evolved: An l2cpd crash will occur when specific LLDP packets are received
An Improper Validation of Specified Quantity in Input vulnerability in the Layer-2 control protocols daemon (l2cpd) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated adjacent attacker who sends specific LLDP packets to cause a Denial of Service(DoS).
This issue occurs when specific LLDP packets are received and telemetry polling is being done on the device. The impact of the l2cpd crash is reinitialization of STP protocols (RSTP, MSTP or VSTP), and MVRP and ERP. Also, if any services depend on LLDP state (like PoE or VoIP device recognition), then these will also be affected.
This issue affects:
Juniper Networks Junos OS
- All versions prior to 20.4R3-S8;
- 21.1 version 21.1R1 and later versions;
- 21.2 versions prior to 21.2R3-S5;
- 21.3 versions prior to 21.3R3-S4;
- 21.4 versions prior to 21.4R3-S3;
- 22.1 versions prior to 22.1R3-S2;
- 22.2 versions prior to 22.2R3;
- 22.3 versions prior to 22.3R2-S2;
- 22.4 versions prior to 22.4R2;
Juniper Networks Junos OS Evolved
- All versions prior to 20.4R3-S8-EVO;
- 21.1 version 21.1R1-EVO and later versions;
- 21.2 versions prior to 21.2R3-S5-EVO;
- 21.3 versions prior to 21.3R3-S4-EVO;
- 21.4 versions prior to 21.4R3-S3-EVO;
- 22.1 versions prior to 22.1R3-S2-EVO;
- 22.2 versions prior to 22.2R3-EVO;
- 22.3 versions prior to 22.3R2-S2-EVO;
- 22.4 versions prior to 22.4R1-S1-EVO;
Attack profile
How easy it is to exploit
- Attack vector
- Adjacent network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
Junos OS and Junos OS Evolved: An l2cpd crash will occur when specific LLDP packets are received
An Improper Validation of Specified Quantity in Input vulnerability in the Layer-2 control protocols daemon (l2cpd) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated adjacent attacker who sends specific LLDP packets to cause a Denial of Service(DoS).
This issue occurs when specific LLDP packets are received and telemetry polling is being done on the device. The impact of the l2cpd crash is reinitialization of STP protocols (RSTP, MSTP or VSTP), and MVRP and ERP. Also, if any services depend on LLDP state (like PoE or VoIP device recognition), then these will also be affected.
This issue affects:
Juniper Networks Junos OS
- All versions prior to 20.4R3-S8;
- 21.1 version 21.1R1 and later versions;
- 21.2 versions prior to 21.2R3-S5;
- 21.3 versions prior to 21.3R3-S4;
- 21.4 versions prior to 21.4R3-S3;
- 22.1 versions prior to 22.1R3-S2;
- 22.2 versions prior to 22.2R3;
- 22.3 versions prior to 22.3R2-S2;
- 22.4 versions prior to 22.4R2;
Juniper Networks Junos OS Evolved
- All versions prior to 20.4R3-S8-EVO;
- 21.1 version 21.1R1-EVO and later versions;
- 21.2 versions prior to 21.2R3-S5-EVO;
- 21.3 versions prior to 21.3R3-S4-EVO;
- 21.4 versions prior to 21.4R3-S3-EVO;
- 22.1 versions prior to 22.1R3-S2-EVO;
- 22.2 versions prior to 22.2R3-EVO;
- 22.3 versions prior to 22.3R2-S2-EVO;
- 22.4 versions prior to 22.4R1-S1-EVO;
- Record
CVE-2023-36839- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-1284
- Updated
- 2026-11-02
EUVDEUVD-2023-40759
An Improper Validation of Specified Quantity in Input vulnerability in the Layer-2 control protocols daemon (l2cpd) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated adjacent attacker who sends specific LLDP packets to cause a Denial of Service(DoS).
This issue occurs when specific LLDP packets are received and telemetry polling is being done on the device. The impact of the l2cpd crash is reinitialization of STP protocols (RSTP, MSTP or VSTP), and MVRP and ERP. Also, if any services depend on LLDP state (like PoE or VoIP device recognition), then these will also be affected.
This issue affects:
Juniper Networks Junos OS
- All versions prior to 20.4R3-S8;
- 21.1 version 21.1R1 and later versions;
- 21.2 versions prior to 21.2R3-S5;
- 21.3 versions prior to 21.3R3-S4;
- 21.4 versions prior to 21.4R3-S3;
- 22.1 versions prior to 22.1R3-S2;
- 22.2 versions prior to 22.2R3;
- 22.3 versions prior to 22.3R2-S2;
- 22.4 versions prior to 22.4R2;
Juniper Networks Junos OS Evolved
- All versions prior to 20.4R3-S8-EVO;
- 21.1 version 21.1R1-EVO and later versions;
- 21.2 versions prior to 21.2R3-S5-EVO;
- 21.3 versions prior to 21.3R3-S4-EVO;
- 21.4 versions prior to 21.4R3-S3-EVO;
- 22.1 versions prior to 22.1R3-S2-EVO;
- 22.2 versions prior to 22.2R3-EVO;
- 22.3 versions prior to 22.3R2-S2-EVO;
- 22.4 versions prior to 22.4R1-S1-EVO;
- Record
EUVD-2023-40759- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-wr6j-q48c-hx4c
An Improper Validation of Specified Quantity in Input vulnerability in the Layer-2 control...
An Improper Validation of Specified Quantity in Input vulnerability in the Layer-2 control protocols daemon (l2cpd) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated adjacent attacker who sends specific LLDP packets to cause a Denial of Service(DoS).
This issue occurs when specific LLDP packets are received and telemetry polling is being done on the device. The impact of the l2cpd crash is reinitialization of STP protocols (RSTP, MSTP or VSTP), and MVRP and ERP. Also, if any services depend on LLDP state (like PoE or VoIP device recognition), then these will also be affected.
This issue affects:
Juniper Networks Junos OS
- All versions prior to 20.4R3-S8;
- 21.1 version 21.1R1 and later versions;
- 21.2 versions prior to 21.2R3-S5;
- 21.3 versions prior to 21.3R3-S4;
- 21.4 versions prior to 21.4R3-S3;
- 22.1 versions prior to 22.1R3-S2;
- 22.2 versions prior to 22.2R3;
- 22.3 versions prior to 22.3R2-S2;
- 22.4 versions prior to 22.4R2;
Juniper Networks Junos OS Evolved
- All versions prior to 20.4R3-S8-EVO;
- 21.1 version 21.1R1-EVO and later versions;
- 21.2 versions prior to 21.2R3-S5-EVO;
- 21.3 versions prior to 21.3R3-S4-EVO;
- 21.4 versions prior to 21.4R3-S3-EVO;
- 22.1 versions prior to 22.1R3-S2-EVO;
- 22.2 versions prior to 22.2R3-EVO;
- 22.3 versions prior to 22.3R2-S2-EVO;
- 22.4 versions prior to 22.4R1-S1-EVO;
- Record
GHSA-wr6j-q48c-hx4c- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-1284
- Updated
- 2026-11-02
NVD
An Improper Validation of Specified Quantity in Input vulnerability in the Layer-2 control protocols daemon (l2cpd) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated adjacent attacker who sends specific LLDP packets to cause a Denial of Service(DoS).
This issue occurs when specific LLDP packets are received and telemetry polling is being done on the device. The impact of the l2cpd crash is reinitialization of STP protocols (RSTP, MSTP or VSTP), and MVRP and ERP. Also, if any services depend on LLDP state (like PoE or VoIP device recognition), then these will also be affected.
This issue affects:
Juniper Networks Junos OS
- All versions prior to 20.4R3-S8;
- 21.1 version 21.1R1 and later versions;
- 21.2 versions prior to 21.2R3-S5;
- 21.3 versions prior to 21.3R3-S4;
- 21.4 versions prior to 21.4R3-S3;
- 22.1 versions prior to 22.1R3-S2;
- 22.2 versions prior to 22.2R3;
- 22.3 versions prior to 22.3R2-S2;
- 22.4 versions prior to 22.4R2;
Juniper Networks Junos OS Evolved
- All versions prior to 20.4R3-S8-EVO;
- 21.1 version 21.1R1-EVO and later versions;
- 21.2 versions prior to 21.2R3-S5-EVO;
- 21.3 versions prior to 21.3R3-S4-EVO;
- 21.4 versions prior to 21.4R3-S3-EVO;
- 22.1 versions prior to 22.1R3-S2-EVO;
- 22.2 versions prior to 22.2R3-EVO;
- 22.3 versions prior to 22.3R2-S2-EVO;
- 22.4 versions prior to 22.4R1-S1-EVO;
- Record
CVE-2023-36839- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-1284
- Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases, published | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2023-36839 is a medium vulnerability (CVSS 6.5) in Juniper Junos, published October 12, 2023. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.30%, the 23rd percentile. No source names a fixed version.